Relay system



March 18, 1930. |-||RT 7 1,751,330

RELAY SYSTEM Filed Jan. 29, 1929 Fig.4

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Patented Mar. 18, 1930 UNITED STATES PATENT OFFICE FRANZ HIRT, OF BERLIN-STEGLITZ, GERMANY, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK RELAY SYSTEM Application filed January 29, 1929, Serial No. 335,980, and inv Germany February 2, 1928.

My invention relates to relay systems embodylng electric discharge devices, and. especially to relay systems used to operate safety or signalling devices on railways.

In such relay systems reliability is absolutely essential and all possible precautions must be taken to insure this reliability. The systems hitherto utilized for controlling railway safety and signalling devices have usually included a discharge device, a current source, a relay to be operated and an apparatus cooperating with the track device, all connected in series and arranged to operate when influenced by the cooperating appara- 5 tus located on the track. Such arrangements are unsatisfactory due to the fact that current flows in the circuit only when it is desired to operate the relay'or other device. If the apparatus becomes inoperative under these conditions, it cannot be immediately detected and may be the cause of serious accidents.

In accordance with my invention the inclividual devices of a system as above described, are connected in parallel with each other and the relay is caused to operate when the resistance of the discharge device is broken down by a potential impulse of predetermined magnitude.

My invention will be better understood from the following description when considered in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

Fig. 1 of the drawing illustrates a relay system embodying my invention; and Figs. 2, 3 and 4 illustrate modifications thereof.

Referring to the drawing in detail, Fig. 1 illustrates an inductance coil 10 which is located on a railway track, is connected in parallel with a condenser 11 and is controlled by a short-circuiting switch 12. The coil 10 is arranged to be brought into inductive relation with a coil 13 which is mounted on the locomotive. The coil 13 is connected to an alternating current source 15 in series with a winding 14 of a transformer 16. A second winding 17 of the transformer 16 is also connected to the source 15 and in series with a coil 18. The windings 14 and 17 are so arranged that their respective magnetic fields are balanced or cancel each other when coil 10 is not near the coil 13. A third winding 19 of the transformer 16 is connected across the electrodes 20 and 21 of a glow-discharge device 22.

An operating relay 23 is also connected across the discharge device 22. This relay may be utilized to release emergency brakes, signalling device or other apparatus, and is arranged to operate upon a reduction of current in its coil. A rectifier 25 is connected between the source 15 and relay 23 when the latter is a D. C. device.

The discharge device 22 is connected to the and 17 are arranged to generate magnetic fields which cancel each other so that the winding 19 is under these conditions energized only by current from the source 15. The relay 23is energized by current flowing from the -soiirce 15 through the impedance 24 and the rectifier 25. The potential applied between electrodes of the discharge device 22 is made to assume a value just below that at which the device begins to pass current.

When the locomotive passes over one of the track coils 19, the reactivedrop of the winding 13 will change and the magnetic balance between the two transformer coils 14 and 17 is disturbed so that a potential is induced in the coil 19. This potential is applied to the electrodes of the discharge device and breaks down the resistance of the'device 22 so that a current flows therethrough. Due to this current the potential across the relay, and consequently the current through it, is reduced and the relay is caused to operate.

Fig. 2 illustrates a modification of my invention in which a three-electrode device 26, provided with electrodes 20, 27 and 28, is used instead of the two-electrode device 22. In

reduced sufficiently to cause it to operate.

With this type of discharge device any fault in the device, as well as in any part ofthe system, can immediately .be detected.

Fig. 3 is a further modification in which a filament electrode 29 is substituted for the electrode 20', and the relay 23 is connected to the source 15 in series therewith. The

impedance 24 is replaced by a transformer 30. The other features, of this modification will be apparent in view of the foregoing explanation.

Fig. 4 is a further modification in which the ignition winding 19 is tapped at its midpoint 31. In the arrangements of Figs. 1,

2 and 3, the current flowing in winding 19' due to the potential of source 15 may, under certain conditions, have a disturbing effect upon the; balance between the currents in windings 14 and 17, of the transformer 16. In the arrangement of Fig. 4 the possibility of such disturbance is avoided by tapping the 'winding and causing the current to divide j so that variations in the current in either part will be cancelled by corresponding variations in the other, and so that the potential induced across the whole winding due to'the unbalancing in the windings 1'5 and 17 will still be the same as in the previous arrangements. In this manner the potential necessary to start the current flow in the discharge device can be obtained with the same number of turns as in the previous arrangement.

- What I claim as new and desire to secure by Letters Patent of the United States is 1. The combination .-of 'current supply means, a relay. connected to said supply means, a glow'tube connected to said supply means in parallel with said relay and operable to transmit current only at a voltage exceeding that of sai supply means, and means for subjecting said tube to' a voltage exceeding that of said supply means.

2. The combination of current supply means, a relay connected to said supply means, a glow tube connected to said supply 7 means in parallel with said relay and operable to transmit current only at a voltage means including a transformer provided with Ysubjecting'said tube to a voltage exceeding that oisaid supply means.

.3. The combination of current supply means, a relay connected to .said supply means, a glow tube connected to said supply said relay, and means for subjecting one of said magnetically balanced coils to a voltage whereby the induced voltageof said tertiary winding is caused to exceed that of said supply means.

4. The combination 0i alternating current supply means, a rectifying element, a relay connected to said supply means through said rectifying element, a,glow discharge element connected in shunt to said relay and operable to transmit current only at a voltage exceeding that applied to said relay by said supply means, and means for causing current to be transmitted through'said glow discharge element.

5. A relay system including a glow discharge device provided with a plurality of electrodes, a relay connected in parallel with said device and arranged to be energized by current flowing between two of said electrodes, and means for causing current flow between another pair of said electrodes to deenergize said relay. 6. A relay system including a glow discharge device provided with a plurality of electrodes, a relay connected in parallel with one pair of said electrodes and in series with another pair of said electrodes, and means arranged to transmit current through said .series connectedelectrodes for energizing said relay and through'said parallel connected electrodes for deenergizing said relay.

, In witness whereof I have hereunto set my hand this 12th day of J anuar 1929.

- FR Z; HIRT. I

3 exceeding that of said supply means, and- 

